Subject: Re: shutdown(8) Heisenbug?
To: None <>
From: John Darrow <>
List: current-users
Date: 09/28/1999 23:15:17
On 1999/09/28, Mason Loring Bliss wrote:
>For a while now, up to and including a sup and build this past Sunday, I've
>had my machine essentially hang at shutdown time. It takes forever to sync
>the disks, and after the sync message the machine never reboots at all - it
>just hangs, and on reboot my root partition (but not my other partitions)
>is run through fsck for cleaning.
>Has anyone else seen this, or is this yet another unique feature of my personal
>environment? <grin>

I did have just once recently when a shutdown got through the 'syncing
disks.... done' stage and then just sat there.

However, I've been running into a different problem.  It will take forever
to get to the 'syncing disks' stage, and then be unable to flush the last
few buffers, thus 'giving up' and forcing a fsck of all partitions upon
boot.  How many buffers would differ between machines, but would be
consistent from reboot to reboot on the same machine.  I eventually
tracked it down to having an mfs mounted - the mount_mfs process would
hang in a wait state something like 'vflushbuf' (sorry, I don't remember
exact state, and I don't have a machine I can reboot right not to check).
If I unmounted my mfs /tmp as part of rc.shutdown (after xdm is killed,
which uses a socket in /tmp), then the sync completes, and the reboot
procedes quickly, leaving the disks marked clean.

As another data point, I seem to remember that if I manually ran rc.shutdown,
then unmounted all but ffs and mfs drives, then did 'reboot' instead of
'shutdown -r now', the syncing worked fine, though I can't figure out why
this would work and shutdown wouldn't...


John Darrow - Senior Technical Specialist               Office: 630/752-5201
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